This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Oligodendrocyte progenitor cells (OPCs) can become myelin-forming oligodendrocytes (OLs) in the central nervous system (CNS). OPCs migrate to demyelinating lesions in patients with multiple sclerosis (MS) but often fail to mature into OLs that remyelinate demyelinated axons. Remyelination failure leads to long-term neurological deficits in MS patients. We previously found that a polysaccharide called hyaluronan (HA) accumulates in MS patient lesions. Our preliminary data indicate that OPCs express hyaluronidases, enzymes that break-down HA, and that breakdown products of HA inhibit the maturation of OPCs into myelin-forming OLs. Furthermore, these HA breakdown products inhibit remyelination and a drug that inhibits hyaluronidase activity can promote OPC maturation in vitro. Our hypothesis is that remyelination failure can be reversed by pharmacologically blocking hyaluronidase activity. Here, we aim to: (1) Identify indole carboxamide and other derivatives that inhibit hyaluronidase activity and promote OPC maturation in vitro. (2) Test if systemic suppression of hyaluronidase activity promotes remyelination in mice with experimentally-induced demyelinating diseases.